ABSTRACT ? PROJECT 2 Although aging is extremely complex, the natural occurrence of genetic variants in humans that affect longevity and healthspan offer an ideal starting point for the systematic identification of targets for interventions that extend human healthspan. Based on the genetically homogeneous Ashkenazi Jewish centenarian resource at the Albert Einstein College of Medicine, for which whole genome and whole exome sequences are now available, we now are able to identify rare, functional genetic variants, pathways and microRNAs associated with healthy longevity that represent potential targets for drug discovery. However, there still is a key need to validate the putative rare variants, pathways and miRNAs linked to longevity in a more defined model system. Here we propose to use mouse models of accelerated and natural aging to not only validate the rare variants and miRNAs identified in Project 1, but to test and validate compounds targeting these rare variants, miRNAs and associated pathways provided by Project 3. We developed a mouse model of accelerated aging (Ercc1-/? mice) and demonstrated that there is a highly significant correlation between the functional, histopathologic, ultra-structural and gene expression changes in liver, cornea, kidney, bone, muscle and bone marrow isolated from 18-20 week-old Ercc1-/? mice and 2-3 year-old wild-type mice. Furthermore, we established that spontaneous, oxidative DNA lesions, cellular senescence and stem cell dysfunction accumulate more rapidly in Ercc1-/? mice than in normal littermates, similar to old wild-type mice. These results strongly suggest that Ercc1-/? age similarly to naturally aging mice, just in an accelerated manner. Thus we are proposing to use both Ercc1-/? and naturally aged mice to validate the different rare variants and miRNAs identified by Project 1 and test compounds targeting these rare variant, miRNAs and associated pathways developed in Project 3. In this regard, we already have used the Ercc1-/? mouse model of accelerated aging to demonstrate that reduction in ATM and NF-?B activity, identified by Project 2 as affected by longevity associated rare variants, generated by heterozygosity in ATM and p65/RelA respectively, extend healthspan. Similarly, Ercc1-/? mice carrying two mutations in the NEMO/IKK? subunit of IKK, preventing activation of NF-?B, by DNA damage, appears to extend healthspan. We also have demonstrated the utility of using Ercc1-/? mice for testing therapeutic interventions where inhibitors of IKK, mitochondrial-targeted free radical scavengers, several different senolytic drugs and young stem cells are able to extend healthspan. The successful completion of the proposed experiments will validate the identified human variants as extending healthy aging and identify therapeutic strategies for the extension of healthspan.